Legio VI Parthica: one of the legions of the later Roman empire.
The name of this unit is a deliberate archaism: when it was created, the Parthian empire, which had once threatened Rome's eastern frontier, had already been replaced by the Sasanian empire.
This legion was created by the emperor Diocletian (284-305), who reorganized the eastern frontier of the Roman empire. Originally, it defended one of the provinces between the Euphrates and the Tigris, but in the catalogue of late-fourth century military units that is included in the Notitia Dignitatum, it is mentioned as part of the mobile field army of the Orient. The change may be caused by the loss of the eastern provinces after the disastrous Persian campaign of the emperor Julianus Apostata (363).